Contents

Introduction· 1

Prerequisites· 1

Example: Configuring IS-IS· 1

Network configuration· 1

Analysis· 2

Applicable hardware and software versions· 2

Restrictions and guidelines· 3

Procedures· 3

Configuring Switch A· 3

Configuring Switch B· 3

Configuring Switch C·· 4

Configuring Switch D·· 4

Configuring Switch E· 5

Verifying the configuration· 6

Configuration files· 7

Introduction

This document provides IS-IS configuration examples.

Prerequisites

The configuration examples in this document were created and verified in a lab environment, and all the devices were started with the factory default configuration. When you are working on a live network, make sure you understand the potential impact of every command on your network.

This document assumes that you have basic knowledge of IS-IS.

Example: Configuring IS-IS

Network configuration

As shown in Figure 1, the company's headquarters and the branch run IS-IS. The partner runs OSPF.

Configure the switches to meet the following requirements:

·     The marketing department can reach the finance department, the branch, and the partner.

·     The finance department and the branch cannot reach each other, and the branch does not have a route to the finance department.

·     When the IS-IS process on Switch C restarts, the communication is not interrupted.

Figure 1 Network diagram

Analysis

To allow communication between the marketing department and the finance department, configure Switch A and Switch B in Area 10 as Level-1 routers.

To allow communication between the marketing department and the partner, configure route redistribution between IS-IS and OSPF on Switch D.

To ensure that the branch does not have a route to the finance department, configure Switch C to use a prefix list to advertise only network 10.100.1.0/24 to Level-2.

To ensure that the communication is not interrupted when the IS-IS process on Switch C restarts, enable IS-IS Graceful Restart (GR) on Switch C.

Applicable hardware and software versions

The following matrix shows the hardware and software versions to which this configuration example is applicable:

Restrictions and guidelines

To avoid blackhole routes, do not change the network topology during the IS-IS GR process.

Procedures

Configuring Switch A

# Configure an IP address for VLAN-interface 11.

<SwitchA> system-view

[SwitchA] interface vlan-interface 11

[SwitchA-Vlan-interface11] ip address 192.168.1.1 24

[SwitchA-Vlan-interface11] quit

# Configure IP addresses for other interfaces, as shown in Figure 1. (Details not shown.)

# Configure IS-IS.

[SwitchA] isis 1

[SwitchA-isis-1] is-level level-1

[SwitchA-isis-1] network-entity 10.1921.6800.1001.00

[SwitchA-isis-1] quit

[SwitchA] interface vlan-interface 11

[SwitchA–Vlan-interface11] isis enable 1

[SwitchA–Vlan-interface11] quit

[SwitchA] interface vlan-interface 100

[SwitchA–Vlan-interface100] isis enable 1

[SwitchA–Vlan-interface100] quit

Configuring Switch B

# Configure an IP address for VLAN-interface 12.

<SwitchB> system-view

[SwitchB] interface vlan-interface 12

[SwitchB-Vlan-interface12] ip address 192.168.2.1 24

[SwitchB-Vlan-interface12] quit

# Configure IP addresses for other interfaces, as shown in Figure 1. (Details not shown.)

# Configure IS-IS.

[SwitchB] isis 1

[SwitchB-isis-1] is-level level-1

[SwitchB-isis-1] network-entity 10.1921.6800.2001.00

[SwitchB-isis-1] quit

[SwitchB] interface vlan-interface 12

[SwitchB–Vlan-interface12] isis enable 1

[SwitchB–Vlan-interface12] quit

[SwitchB] interface vlan-interface 200

[SwitchB–Vlan-interface 200] isis enable 1

[SwitchB–Vlan-interface 200] quit

Configuring Switch C

# Configure an IP address for VLAN-interface 11.

<SwitchC> system-view

[SwitchC] interface vlan-interface 11

[SwitchC-Vlan-interface11] ip address 192.168.1.2 24

[SwitchC-Vlan-interface11] quit

# Configure IP addresses for other interfaces, as shown in Figure 1. (Details not shown.)

# Configure IS-IS.

[SwitchC] isis 1

[SwitchC-isis-1] network-entity 10.1921.6801.0001.00

[SwitchC-isis-1] quit

[SwitchC] interface vlan-interface 10

[SwitchC–Vlan-interface10] isis enable 1

[SwitchC–Vlan-interface10] quit

[SwitchC] interface vlan-interface 11

[SwitchC–Vlan-interface11] isis enable 1

[SwitchC–Vlan-interface11] quit

[SwitchC] interface vlan-interface 12

[SwitchC–Vlan-interface12] isis enable 1

[SwitchC–Vlan-interface12] quit

# Configure route leaking from Level-1 to Level-2, and use prefix list 1 to advertise only network 10.100.1.0/24 to Level-2.

[SwitchC] ip prefix-list 1 permit 10.100.1.0 24

[SwitchC] isis 1

[SwitchC] address-family ipv4

[SwitchC-isis-1-ipv4] import-route isis level-1 into level-2 filter-policy prefix-list 1

[SwitchC-isis-1-ipv4] quit

 # Enable IS-IS GR.

[SwitchC-isis-1] graceful-restart

[SwitchC-isis-1] quit

Configuring Switch D

# Configure an IP address for VLAN-interface 10.

<SwitchD> system-view

[SwitchD] interface vlan-interface 10

[SwitchD-Vlan-interface10] ip address 192.168.10.2 24

[SwitchD-Vlan-interface10] quit

# Configure IP addresses for other interfaces, as shown in Figure 1. (Details not shown.)

# Configure IS-IS.

[SwitchD] isis 1

[SwitchD-isis-1] is-level level-2

[SwitchD-isis-1] network-entity 10.1921.6802.0001.00

[SwitchD-isis-1] quit

[SwitchD] interface vlan-interface 10

[SwitchD–Vlan-interface10] isis enable 1

[SwitchD–Vlan-interface10] quit

[SwitchD] interface vlan-interface 20

[SwitchD–Vlan-interface20] isis enable 1

[SwitchD–Vlan-interface20] quit

# Configure OSPF.

[SwitchD] ospf

[SwitchD-ospf-1] area 0

[SwitchD-ospf-1-area-0.0.0.0] network 192.168.20.0 0.0.0.255

[SwitchD-ospf-1-area-0.0.0.0] quit

[SwitchD-ospf-1] quit

# Redistribute OSPF and direct routes into IS-IS

[SwitchD] isis 1

[SwitchD] address-family ipv4

[SwitchD-isis-1-ipv4] import-route ospf

[SwitchD-isis-1-ipv4] import-route direct

[SwitchD-isis-1-ipv4] quit

[SwitchD-isis-1] quit

# Redistribute IS-IS and direct routes into OSPF.

[SwitchD] ospf 1

[SwitchD-ospf-1] import-route isis 1

[SwitchD-ospf-1] import-route direct

Configuring Switch E

# Configure an IP address for VLAN-interface 20.

<SwitchE> system-view

[SwitchE] interface vlan-interface20

[SwitchE-Vlan-interface12] ip address 192.168.20.2 24

[SwitchE-Vlan-interface12] quit

# Configure IP addresses for other interfaces, as shown in Figure 1. (Details not shown.)

# Configure OSPF.

[SwitchE] ospf

[SwitchE-ospf-1] area 0

[SwitchE-ospf-1-area-0.0.0.0] network 192.168.20.0 0.0.0.255

[SwitchE-ospf-1-area-0.0.0.0] network 10.200.1.0 0.0.0.255

[SwitchE-ospf-1-area-0.0.0.0] quit

[SwitchE-ospf-1] quit

Verifying the configuration

# Verify that the branch can reach the marketing department, but cannot reach the finance department.

[SwitchD] display isis route

                         Route information for IS-IS(1)

                         ------------------------------

                         Level-2 IPv4 Forwarding Table

                         -----------------------------

 IPv4 Destination     IntCost    ExtCost ExitInterface   NextHop         Flags

-------------------------------------------------------------------------------

 192.168.10.0/24      10         NULL    Vlan10          Direct          D/L/-

 192.168.1.0/24       20         NULL    Vlan10          192.168.10.1    R/-/-

 10.100.1.0/24        30         NULL    Vlan10          192.168.10.1    R/-/-

 192.168.2.0/24       20         NULL    Vlan10          192.168.10.1    R/-/-

      Flags: D-Direct, R-Added to Rib, L-Advertised in LSPs, U-Up/Down bit set

# Verify that the marketing department can communicate with the partner.

·     Display the IS-IS routing table on Switch C.

[SwitchC] display isis route

                         Route information for IS-IS(1)

                         ------------------------------

                         Level-1 IPv4 Forwarding Table

                         -----------------------------

 IPv4 Destination     IntCost    ExtCost ExitInterface   NextHop         Flags

-------------------------------------------------------------------------------

 192.168.10.0/24      10         NULL    Vlan10          Direct          D/L/-

 192.168.1.0/24       10         NULL    Vlan11          Direct          D/L/-

 10.100.1.0/24        20         NULL    Vlan11          192.168.1.1     R/L/-

 10.100.2.0/24        20         NULL    Vlan12          192.168.2.1     R/-/-

 192.168.2.0/24       10         NULL    Vlan12          Direct          D/L/-

      Flags: D-Direct, R-Added to Rib, L-Advertised in LSPs, U-Up/Down bit set

                         Level-2 IPv4 Forwarding Table

                         -----------------------------

 IPv4 Destination     IntCost    ExtCost ExitInterface   NextHop         Flags

-------------------------------------------------------------------------------

 192.168.10.0/24      10         NULL    Vlan10          Direct          D/L/-

 10.200.1.0/24        10         0       Vlan10          192.168.10.2    R/-/-

 192.168.20.0/24      10         0       Vlan10          192.168.10.2    R/-/-

 192.168.1.0/24       10         NULL    Vlan11          Direct          D/L/-

 192.168.2.0/24       10         NULL    Vlan12          Direct          D/L/-

      Flags: D-Direct, R-Added to Rib, L-Advertised in LSPs, U-Up/Down bit set

·     Ping 10.200.1.1 from Switch A.

[SwitchA] ping 10.200.1.1

Ping 10.200.1.1 (10.200.1.1): 56 data bytes, press CTRL_C to break

56 bytes from 10.200.1.1: icmp_seq=0 ttl=254 time=1.862 ms

56 bytes from 10.200.1.1: icmp_seq=1 ttl=254 time=2.969 ms

56 bytes from 10.200.1.1: icmp_seq=2 ttl=254 time=1.402 ms

56 bytes from 10.200.1.1: icmp_seq=3 ttl=254 time=1.324 ms

56 bytes from 10.200.1.1: icmp_seq=4 ttl=254 time=1.510 ms

--- Ping statistics for 10.200.1.1 ---

5 packet(s) transmitted, 5 packet(s) received, 0.0% packet loss

round-trip min/avg/max/std-dev = 1.324/1.813/2.969/0.606 ms

# Verify that the communication is not interrupted when the IS-IS process restarts.

·     Ping Switch B from Switch A.

[SwitchA] ping -c 10000 10.100.2.1

Ping 10.100.2.1 (10.100.2.1): 56 data bytes, press CTRL_C to break

56 bytes from 10.100.2.1: icmp_seq=0 ttl=254 time=1.185 ms

56 bytes from 10.100.2.1: icmp_seq=1 ttl=254 time=1.087 ms

…

·     Restart the IS-IS process on Switch C.

[SwitchC] reset isis all graceful-restart

Reset IS-IS process? [Y/N] :y

# Ping Switch B from Switch A.

[SwitchA] ping -c 10000 10.100.2.1

Ping 10.100.2.1 (10.100.2.1): 56 data bytes, press CTRL_C to break

56 bytes from 10.100.2.1: icmp_seq=0 ttl=254 time=1.185 ms

56 bytes from 10.100.2.1: icmp_seq=1 ttl=254 time=1.087 ms

56 bytes from 13.13.13.3: icmp_seq=2 ttl=254 time=1.672 ms

56 bytes from 13.13.13.3: icmp_seq=3 ttl=254 time=1.751 ms

56 bytes from 13.13.13.3: icmp_seq=4 ttl=254 time=1.816 ms

56 bytes from 13.13.13.3: icmp_seq=5 ttl=254 time=1.814 ms

# Check the IS-IS GR state on Switch C.

[SwitchC] display isis graceful-restart status

                        Restart information for IS-IS(1)

                        --------------------------------

Restart status: COMPLETE

Restart phase: Finish

Restart t1: 3, count 10; Restart t2: 60; Restart t3: 300

SA Bit: supported

                          Level-1 restart information

                          ---------------------------

Total number of interfaces: 3

Number of waiting LSPs: 0

                          Level-2 restart information

                          ---------------------------

Total number of interfaces: 3

Number of waiting LSPs: 0

Configuration files

·     Switch A:

#

isis 1

 is-level level-1

 network-entity 10.1921.6800.1001.00

#

vlan 11

#

vlan 100

#

interface Vlan-interface11

 ip address 192.168.1.1 255.255.255.0

 isis enable 1

#

interface Vlan-interface100

 ip address 10.100.1.1 255.255.255.0

 isis enable 1

#

·     Switch B:

#

isis 1

 is-level level-1

 network-entity 10.1921.6800.2001.00

#

vlan 12

#

vlan 200

#

interface Vlan-interface12

 ip address 192.168.2.1 255.255.255.0

 isis enable 1

#

interface Vlan-interface200

 ip address 10.100.2.1 255.255.255.0

 isis enable 1

#

·     Switch C:

#

isis 1

 graceful-restart

 network-entity 10.1921.6801.0001.00

 #

 address-family ipv4 unicast

  import-route isis level-1 into level-2 filter-policy prefix-list 1

#

vlan 11 to 13

#

interface Vlan-interface11

 ip address 192.168.1.2 255.255.255.0

 isis enable 1

#

interface Vlan-interface12

 ip address 192.168.2.2 255.255.255.0

 isis enable 1

#

interface Vlan-interface13

 ip address 192.168.10.1 255.255.255.0

 isis enable 1

#

 ip prefix-list 1 index 10 permit 10.100.1.0 24

#

·     Switch D:

#

isis 1

 is-level level-2

 network-entity 20.1921.6802.0001.00

#

 address-family ipv4 unicast

  import-route direct

  import-route ospf 1

#

ospf 1

 import-route direct

 import-route isis 1

 area 0.0.0.0

  network 192.168.20.0 0.0.0.255

#

vlan 10

#

vlan 20

#

interface Vlan-interface10

 ip address 192.168.10.2 255.255.255.0

 isis enable 1

#

interface Vlan-interface20

 ip address 192.168.20.1 255.255.255.0

#

·     Switch E:

#

ospf 1

 area 0.0.0.0

  network 10.200.1.0 0.0.0.255

  network 192.168.20.0 0.0.0.255

#

vlan 20

#

vlan 300

#

interface Vlan-interface20

 ip address 192.168.20.2 255.255.255.0

#

interface Vlan-interface300

 ip address 10.200.1.1 255.255.255.0

#